Lubricant compositions



2,833,714 P n e ay6t-195 LUBRICANT COMPOSI'IIONS Eugene E. Richardson, Hammond, and Roger W. Watson,

I Highland, Ind., assignors to Standard Oil Company,

"Chicago, 111., a corporation of Indiana Application September 28, 1955 Serial No. 537,268

6 Claims. (Cl. 252--32.7)

No Drawing.

This invention pertains to improved lubricant compositions and more particularly pertains to internal combustion engine lubricant compositions which inhibit cam follower pitting and/or wear and which inhibit the sticking of hydraulic valve-lifters.

Many modern automobile engines are designed with hydraulic valve-lifters for smoother and more efiicient engine operation. In the operation of hydraulic valvelifters, the lifters ride .on the cam shaft converting the rotary motion of the cam into a reciprocating motion, which in turn opens and closes the valves. The bottom of the valve-lifter is known as the cam follower. The hydraulic part of the valve-lifter functions by means of a plunger n the inside of the valve lifter barrel,

together with a ball-check and a spring. To obtain higher efficiency and greater horsepower, larger valves,

4 high valve spring pressures and camshafts which produce more rapid valve opening and closing are employed.

In the operation of such engines, greatly increased pressures are encountered where the camshaft lobes come into contact with the faces of the valve-lifters resulting in excessive and severe cam and lifter wear as well as pitting of the cam followers. This wear and/or pitting cannot be adequately inhibited by most present- 'day internal combustion engine crank-case lubricants.

Surprisingly, the type of anti-wear properties which will inhibit piston ring and/or cylinder wear are not necessarily the same as the anti-wear properties necessary to prevent cam and lifter wear and/or pitting; hence many lubricants which are effective in. inhibiting ring and "cylinder wear are ineffective in preventing cam and lifter we A further complicating factor in this problem is caused by the materials used inmaking the camshaft and valve-lifters since different metals and metal combinations are used for this purpose in the various, engines.

Camshaft and valve-lifter combinations of different metals create different requirements on the lubricant in Hence, it is essential for lifter.

It is an object of this invention to provide a lubricant fcojrnposition which will not cause sticking of hydraulic va ve-lifte i whi hv will. inhibi c m follower wear and/or pitting. Another object 'of the invention is to provide a crank-case lubricant which will be substantially "free 'o any tendency tocause valve-lifter sticking and/or msfingsnd which will have cam follower anti-pitting and 3 anti-wear properties. Another object of the invention is to provide an improved lubricant for internal combusti'on engines.

Still another object of the invention is to ester.

, 2 provide a method of preventing the sticking of hydraulic valve-lifters and the pitting and/ or wear of cam followers in internal combustion engines. Other objects and advantages of the invention will become apparent fromthe following description thereof. a

In accordance with the herein described. invention, the above objects can be attained by incorporating in a viscous oil, i. e., an oil having a Saybolt Universal viscosity above about seconds at F., containing about 0.002 and 10% of a phosphorusand sulfurcontaining detergent-type lubricating oil additive, bet-ween about 0.001 and 5% of the polymerization product Of unsaturated fatty acids such as linoleic acid, and between about 0.001 and 5% of stearic acid or its salts. The polymerization products may have a molecularweight between about 400 and 2000. a

The detergent-type lubricating oil additive used is one which contains phosphorus and sulfur. The function of this type of additive is to inhibit the formation of sludge and/ or varnish-like products which are deposited in the engine and/or about the valves and rings of the engine. Detergent additives of this type are usually used in amountsof from about 0.002 to about 10%, and preferably from about 0.01% to about 5%. Among the phosphorusand sulfur-containing addition agents are the neutralized reaction products of a phosphorus sulfide and a hydrocarbon, an alcohol, a ketone, an amine or an Of the phosphorus sulfide reaction product additives, the neutralized reaction products of a phosphorus sulfide, such as a phosphorus penta-sulfide, and a hydrocarbon (note U. S. 2,316,082) are preferred.-

The preferred hydrocarbon used for reaction with the phosphorus sulfide is a mono-olefin hydrocarbon polymer resulting from the polymerization of low molecular weight mono-olefin hydrocarbons, such as propylene, butenes, amylenes or copolymers thereof. Such polymers may be obtained by the polymerization of mono-olefins of less than 6 carbon atoms in the presence of a catalyst, such as sulfuric acid, phosphoric acid, boron fluoride, aluminum chloride or other similar halide catalysts of the Friedel-Crafts type.

The polymers employed are preferably mono-olefin polymers or mixtures of mono-olefin polymers andisomono-olefin polymers having molecular weights ranging from about to about 50,000 or more, and preferably from about 500 to about 10,000. Such polymers can be obtained, for example, by the polymerization in the liquid phase of a hydrocarbon mixture containing monoand isomonoolefins, such as butylene and isobutylene at a temperature of from about 80 F. to about 100 F. in the presence of a metal halide catalyst of the Friedel- Crafts type, such as for example, boron fluoride, aluminum chloride, and the like. In the preparation of these polymers, a hydrocarbon mixture containing isobutylene,

butylenes-and butanes recovered from petroleum gases, .especially those gases produced in the cracking of petroleum oils in themanufacture of gasolinecan be used.

Another suitable polymer is that obtained by polymerizing ammo-ear propene with other close-boiling s atura'ted'hydrocarbons. An aluminum chloride-isooctane complex may be used as the catalyst at 'a temperature of about 50 to 100 F. to produce the polymer which may then be fractionated to a molecular Weight, preferably from about 500 to 1000 or higher.

Parafiinic hydrocarbons such as bright stock residuurns, lubricating oil dist-illates, waxes, and the like can be re- -"-a ':ted' with phosphorus sulfide. Olefins having-'16 to 30 carbon atoms or higher may be reacted with the phosphorus sulfide. Other hydrocarbons that can be reacted with a phosphorus sulfide are aromatic hydrocarbons such as benzene, naphthalene, diphenyl, alkylated aromatic hysolvent by suitable means, such as by distillation.

- wear properties.

dro'carbonssuch as benzene having alkyl substituents containing preferably at least 8 carbon atoms and the like.

The phosphorus sulfide-hydrocarbon reaction product can be readily obtained by reacting a phosphorus sulfide,

*for example P 8 with the hydrocarbon at a temperature of from about 200 Futo about 500 F., and preferably from about 200 F. to about 400 F., using from about 1% to about 50%, and preferably from about 5% to about 25% of thephosphorus sulfide in the reaction. It

- isadvanta geous' to maintain a non-oxidizing atmosphere,

react with the hydrocarbon so thatno further purification becomes necessary; however, an excess amount of phosphorus sulfide can be used and separated from the product by filtration or by dilution with a hydrocarbon solvent,

such as hexane, filtering and subsequently removing the If desired, the reaction product can be further treated with steam at an elevated temperature of fromabout 100 F.

to about 600 F. 1 v

The phosphorus sulfide-hydrocarbon reaction product normally shows a titratable acidity which is neutralized by treatment with a basic reagent. The term neutralized Prior to clayed to remove inorganic acids of phosphorus as describedin U. S. 2,688,612 issued to R. W. Watson September 7, 1954. i

The neutralized phosphorus sulfide-hydrocarbon reaction product can be obtained by treating the acidic reaction product with a suitable basic compound, such as hydroxide, carbonate oxide or sulfide of an alkaline earth metal or an alkali metal, such as for example, potassium hydroxide, sodium hydroxide, sodium sulfide, calcium oxide, lime, barium hydroxide, barium oxide, etc. Other basic reagents can be used, such as for example, ammonia or an alkyl or aryl-substituted ammonia, such as amines.

' The neutralization of the phosphorus sulfide-hydrocarbon reaction product is carried out preferably in a nonoxidizing atmosphere by contacting the acidic reaction product either as such or dissolved in a suitable solvent, such as naphtha with a solution of the basic agent. As an alternative method the reaction product can be treated with solid "alkaline compounds such as KOH, NaOH, Na CO CaO, BaO, .Ba(OH),, Na S, and the like, at an elevated temperature of from about 100 F. to about 600 F. Neutralized reaction products containing a heavy metal constituent, such as for example, tin, titanium, aluminum,

chromium, cobalt, zinc, iron, and the like, can be obtained by reacting a salt of the desired heavy metal with the phosphorus sulfide hydrocarbon reaction product which has been treated with a basic reagent such as abovedescribed.

While the detergent-type additives effectively inhibit the formation of sludge and/ or varnish like products in the engine, they do not possess rust and/ or corrosion inhibiting properties nor do they possess anti-pitting and anti- However, when used in combination with the herein described mixture of the polymerization products of unsaturated fatty acids and with stearic acid, complete engine; protection is obtained.

The unsaturated fatty acids which maybe polymerized are those natural or synthetic mono-carboxylic acids which generally will have two or more unsaturated linkages. 1 If natural fatty acids are employed they will usually have 16 to 26 carbon atoms, most frequently 18 polymers of the unsaturated fatty acids.

carbon atoms, but if synthetic unsaturated fatty acids are used they may have a lesser or greater number of carbon atoms. Examples of the natural fatty acids are those such as linoleic, linolenic, ricinoleic (which upon heating forms linoleic acid), linoleaidic, elaidolinolenic, eleostearic, arachidonic, eicosatrienaic, cetoleic, docosatrienoic and the like. The free fatty acids can be polymerized either thermally or with the assistance of catalysts. A method of thermally polymerizing free fatty acids (see U. S. 2,482,761) consists of hydrolyzing a fat or an oil, adding a small portion of water, and heating in a pressure vessel until substantially all of the diand tri-unsaturated fatty acids present polymerize. The resultant product is then heated at a reduced pressure to distill olf vaporizable constituents, leaving behind the polymerized unsaturated fatty acids. The polymerization reaction is carried out at a temperature of about 300 to 360 C. for about three to eight hours at a pressure varying between and 500 p. s. i. g. The polymerization product may consist of monomers, dimers, trimers, and higher The various fats or oils which may be hydrolyzed to produce the free fatty acids used in the above thermal polymerization are those such as sardine oil, linseed oil, soybean oil, castor oil, peanut oil, palm oil, olive oil, cottonseed oil, sunflower seed oil, and the like.

Another method of preparing the polymerized fatty acids consists of subjecting fats and oils such as have been listed supra (without previous hydrolysis) to a thermal or catalytic polymerization to cause polymerization of the esters of the unsaturated carboxylic acids to the dimers,

I listed supra, polymerizing the methyl esters, removing unpolymerized compounds, saponifying the residual esters and freeing polymerized acids therefrom. The products of catalytic polymerization of semi-drying oils such as the BF; polymerization products of soybean oil, cottonseed oil, or the like also produce polymers suitable for use in the invention.

It should be understood that while various polymerized unsaturated fatty acids may be used, they do not all provide the same effect, and indeed there may be pro nounced differences when used in the composition of this invention. A highly preferred source of the polymerized unsaturated fatty acids is obtained as a by-product still residue in the manufacture of sebacic acid by the dry distillation of castor oil in the presence of sodium hydroxide. A method of obtaining such by-product still residues in the manufacture of sebacic acid is described in U. S. 2,470,849 issued to W. E. Hanson May 24, 1949. The mixture of high molecular weight unsaturatedffatty acids comprises monomers, dimers, trimers and higher polymers in the ratio of from about 45% to about 55% of a monomers and dimers fraction having a molecular weight in the range offrom about 300 to 600, and from about 45% to about 55% of a trimers and higher polymer fraction having a molecular weight in excess of 600. The fatty acid polymers result in part from a thermal polymerization of fatty acid type constituents of the castor oil, and in part from other reactions, such as the intermolecular esterification, of such acid to form high molecular weight products. The acid mixture, which is mainly a mixture of polymeric long chain polybasic carboxylic acids, is further characterized by the following specifications:

ample "about t 0.2%. acids, as well as the amount ofstearic acid used, maybe lecular-weights averaging about 800 or higher are ,par-

ticula'rly'preferred for use in this invention. Especially preferred polymerized unsaturated acids are the polymerization products of acids such as 'linoleic acid having 'a molecular weight between about 400, and 2000, wherein 6 a. improvers, bearing corrosi n inhibitors; frustf irrliibito rs and'thelike.- i

A number of performance tests "fr*eyaluating"fthe I ability of the lubricating 'oil'to inhibit pittirrg and/or wear jthepolymerization products consist of more ,than about 40% ofthe-trimer and higher molecular weight polymers of linoleic acid with the remainder consisting primarily of monomers-and dimers of ,linoleic acid. The polymerization productsof the unsaturated fatty acids'should be'used in an amount between about 0.001 and 5.0% in the oil, preferably between about 0.05 to 2.0%, ,for ex- The amount of polymerized" fatty varied-depending upon the oil in which it is employed, the materials used in making the earn shaft and valvelifters, the valve spring pressures and other factors which affect the degree of pitting and wear.

The stearic acidwhich maybe used may be ordinary commercial stearic acid or a purified type.'of stearic'acid.

Y The actual stearicacid content of such compositionsjmay vary from the 45% stearic acid-55% Hpalmitic acid contained in commercial stearic acid to the'90% stearic acid which is contained in ".c ommercially'gpure stearic acid. The stearic acid may be single-, double-, ortriplepressed, preferably "the latter. It is contained in 'the lubrieating oil base in amounts between about 0.00'1and preferably between about 0.001 and 2%. As in the case ofthe polymerized'unsaturated fatty acid, .the amount of stearic acid may be varied .depending upon the "intensity of pitting and wear which occur andwhichis. due to factors such as valve-spring pressures,the materials used in the making ,of the cam-.shaftand =-valve-1ifters, additives contained in the oil, etc. A suitable amount of stearic acid is usually about=0.0l-to 0.5%. It is to be understood that the amounts of stearic. acid aas specified herein andvin the claims are expressed in terms :of the actual stearic acid content of the-composition containing stearic acid which is employed. Amine salts such as octadecyl amine salt of stearic acid or metal salts such as zinc stearate may be employed in place of the stearic acid if desired. For example, the aliphatic mono-, di-, or poly-amine salts of stearic acid can be used as well as the alkali, alkaline earth or heavy metal salts of stearic acid. The amine salts may be formed in situ by adding the amine to the oil containing the stearic acid.

The phosphorusand sulfur-containing detergent-type additive, the polymerization products of the unsaturated fatty acids, and the stearic acid can be added individually to the base motor oil or they can be pre-mixed in the desired proportions and the resultant mixed product added to the base oil. For example, from about 1 to 25% of the polymerized acids, from about 1 to 25% of stearic acid and from about 98 to about 50% of the detergenttype additive can be pre-mixed at a temperature of about 70 to 150 F. and the mixture then added to the base oil. If desired, concentrates of a suitable lubricating oil base containing to about 50% or more of the herein described mixture of polymerized unsaturated fatty acids, stearic acid, and the phosphorus-, sulfur-containing detergent additive may be used for blending with other hydrocarbon lubricating .oils in the proportions desired for the particular conditions of use to provide a finished product containing the amounts of the individual constituents previously indicated to be useful. The lubricating oil may also contain other additives such as V. I.

as well as its abilityito preverit. rusting' o f the' hydraulic valve lifters' were made; The' '"testsmadefto "determine the anti-pitting and anti-wear properties of the""oil"is known as theL-S-5 test .establishedbydhe Generals-Motors Research Division. The test is made ona 1953 Chevrolet power glide engine equipped with chilled iron llifters, forged steel cams, steel rocker armshafts, malleable iron rockeriarrns and Qperating atd'ISO R. P. Miwithaload of- 30 fbrake: horsepower, :an oil sump temperature of 255 -F., and a wateroutlet temperature of--200 F. Dual valve springs ;-are installed to .give an assembled static valve spring load of"240pounds:at 0.33f0finchvalve I opening. .Thetest is continued for 24.hours-i=at the end of which the cam followers are inspectedfor pitting and over-all wear. The effectiveness of the additives'for preventing .pittin'g of the cam followers is vvshown in the --table which follows. In this-table each sample consisted of Ean SAE 10W-30 oil containing 3.3% of abar'iumcontaining neutralized reaction product of P 8 zanda polybutene of about 1000 molecular :weight, 0.75% of a sulfurized dipentene (35% :sulfur), and =1:0- p..p. 'mxsiliconepolymer anti-foam agent. Various additiveshaving anti-pitting. and-anti-wear properties were added-to different ,sarnplesof the oil containing the barium .sal't, sulfurized :dipentene' and silicone :polymer. The 'results show:

L-S-5 engine tests I Concen I \Roeker; SampleNo. 'Antl-Plttlng andlihti 'trafion, Lifters .Ar'm

Wear Additlve Wt.'Per- 'Pttte'd Seizure cent ' -10 Severe, 0; 3' o. 8. none -Moderate. Oi' none D02" 0. J 0. .none .110. Zine -Stearate 0.

1 Qcta'decylaniine' salt' or stearicacid.

. Sample 1 shows that when no. anti-pitting-anti-wearadditive is added to the oil, 10 of theIZ cam follower surfaces of the hydraulic valve lifters become pitted. Sample 2 shows that although the D-50 acid (inspections and method of manufacture of which have been detailed previously) is somewhat effective for reducing the number of pitted cam-followers, it does not eliminate the problem of pitting and wear completely. Samples 3, 4, and 5 show that when stearic acid (triple pressed) or its salts such as the octadecyl amine salt of stearic acid or zinc stearate are added to the oil containing the phosphorusand sulfur-containing detergent-type additive and the polymerized unsaturated fatty acids, there is no pitting at all of the cam follower surfaces.

An additional series of samples were evaluated to determine the ability of various additives to prevent rusting of the hydraulic valve-lifters. The test employed is called the modified Indiana hydraulic valve lifter rust test. This test is carried out in a Chevrolet Powerglide engine operating at 2500 R. P. M. and a load of 45 B. H. P. with an oil temperature of 120 F. and a water temperature of -95 F. The test engine is operated at these conditions for 20 hours with a 4 hour running and 4 hour olf cycle. At the end of 20 hours the dipstick, rocker arm shaft and valve lifters are inspected for rust. Valve lifters free of rust are rated 10 and badly rusted lifters are rated 1.

The effectiveness of the various additives for preventingrusting and/or corrosion is in the table which follows. Inthis table each sample consisted of an SAE ,about 1000 molecular weight, 0.75% of a sulfurized dipentene (35%;Isulfur), and 10p. p. m. silicone polymer anti-foam agent. Various additives were added to the oil containing the'above ingredients. The results obtained were:

* Modified Indiana hydraulic valve lifter rust test Engine Ratings (Rust) Sarnt ple Additive Amount V Dlpstlck Rocker Valve Arm Litters Test stopped, excessive rust B 0.20, Moderate" Sllgh 0.1g o do 7.0 8 smmAcidn J0 Bllght- Moderate.. L 9.5

When sample 1 was tested the oil containing thedetergent additive caused such severe rusting as to require termination of the test beforeits normal time. a Sample 6 shows that the addition of stearic acid (triple pressed) reduced the amount of'rusting. Similarly sample 7 which contained :the octadecyl amine salt of stearic acid (triple pressed) reduced the amount of: rusting. Evaluation of sample 8 which contained both the polymerized unsaturated fatty acid and stearic acid (triple pressed) showed 'that the'oil containing both such ingredients in addition to the detergent additive reduced rusting of the. valvelitters to a negligible level.

While the present invention'has' been described by the useof our additives in petroleum lubricating oils',other lubricating: oil bases can beemployed such as hydrocar bon oils, natural or synthetic such as those obtained by Although the present invention has been described with 4 reference ,to specific preferred embodiments thereof, the invention is not to be considered as limited thereto'but includes within its scope such modifications and variations as come within the spirit of the appended claims. We claim: i

l. A lubricating oil composition having improved valve lifter anti-pitting and anti-wear properties comprising a major proportion of a lubricating mineral oil base,'between about0.002 and 10% of a phosphorus sulfide-hydrocarbon reaction product which has been neutralized with a basic reagent between about 0.001 and 5% of the polymerization products of those unsaturated fatty acids which have between 16 and 26 carbon atoms per mole cule, said polymerization products having a molecular weight between about 400 and 2000, and between about 0.001 and 5% of at least one saturated fatty acid compound selected from the class consisting of stearic acid and the salts thereof.

2. The composition of claim 1 wherein the basic reagent is an alkaline earth metal compound.

3. The composition of claim 1 wherein the saturated fatty acid compound is stearic acid. b

4. The compositionof claim 1 in which the unsaturated fatty acid is linoleic acid.

I 5. The composition of claim 1 wherein the polymerization products of the unsaturated fatty acids consist of more than about 40% of the trimer and higher molecular weight polymers, the remainder being essentially. monomers and dimers of the unsaturated fatty acids.

6. A lubricating oil composition having improved valve lifter anti-pitting and anti-wear properties comprising a major proportion of a lubricating mineral oil base, between about 0.002 and 10% of a phosphorus sulfide-olefin polymer reaction product whichhas been neutralized with a basic barium compound, between about 0.05 and 2% of the polymerization products of linoleic acid having a molecular weight between about 400 and 2000, said polymerizationproducts consisting of more than about.40% of the trimer and higher molecular weight polymers of linoleic acid and the remainder being essentially mono:

mers and dimers of linoleic acid, and between about 0.001.

and 2% ofstearic acid.

References Cited in the file of this patent UNITED STATES PATENTS r 2,281,676 Cook MayS, 1942 2,316,090 Kelso Apr. 6, 1943 2,631,979 McDermott Nov. 17, 1953 

1. A LUBRICATING OIL COMPOSITION HAVING IMPROVED VALVE LIFTER ANTI-PITTING AND ANTI-WEAR PROPERTIES COMPRISING A MAJOR PROPORTION OF A LUBRICATING MINERAL OIL BASE, BETWEEN ABOUT 0.002 AND 10% OF A PHOSPHORUS SULFIDE-HYDROCARBON REACTION PRODUCT WHICH HAS BEEN NEUTRALIZED WITH A BASIC REAGENT BETWEEN ABOUT 0.001 AND 5% OF THE POLYMERIZATION PRODUCTS OF THOSE UNSATURATED FATTY ACIDS WHICH HAVE BETWEEN 16 AND 26 CARBON ATOMS PER MOLECULE, SAID POLYMERIZATION PRODUCTS HAVING A MOLECULAR WEIGHT BETWEEN ABOUT 400 AND 2000, AND BETWEEN ABOUT 0.001 AND 5% OF AT LEAST ONE SATURATED FATTY ACID COMPOUND SELECTED FROM THE CLASS CONSISTING OF STEARIC ACID AND THE SALTS THEREOF. 